Closers with door stop and hold open devices, panic devices with varying trim and functions, mortising jigs for lock sets and hinges, door coordinators, knockdown and welded frames, changing the swing on metal frames, boring jigs for various backsets, fitting doors into existing frames and beveling using an electric planer, installing a henway ... that's all I could think of off the top of my head.
What's the difference between a left had door and a right hand reverse Mr. Door Expert?
Go ahead, Google it.
The class allows people to practice doing all that stuff so
that when they get to a job, it won't be their first time.